Oracle database

An Oracle database, strictly speaking, is a collection of data managed by an Oracle database management system or DBMS. The term "Oracle database" is sometimes imprecisely used to refer to the DBMS software itself. This error is made in the title of this article and below.

The Oracle database management system can be referred to without ambiguity as Oracle DBMS or, the databases which it manages being relational in character, as Oracle RDBMS.

The very useful distinction between data managed by Oracle, an Oracle database, and the Oracle RDBMS is blurred by Oracle Corporation itself when they refer nowadays to the Oracle RDBMS, the software they sell to manage databases, as the Oracle Database. The distinction between the managed data (the database) and the software which manages the data (the DBMS / RDBMS) relies, in Oracle's marketing literature, on the capitalisation of the word database.

The Oracle DBMS is produced and marketed by Oracle Corporation. The Oracle DBMS is extensively used by many database applications on most popular computing platforms. Oracle database was developed by Larry Ellison, along with friends and former coworkers Bob Miner and Ed Oates, who had started a consultancy called Software Development Laboratories (SDL). They called their finished product Oracle, after the code name of a CIA-funded project they had worked on at a previous employer, Ampex.

Database structure

Oracle stores data logically in the form of tablespaces and physically in the form of data files. Tablespaces can contain various types of segments, for example, Data Segments, Index Segments etc. Segments in turn are made up of one or more extents. Extents are grouped based on contiguous data blocks. Data blocks are the basic units of data storage. At the physical level, data files are made up of one or more data blocks, where the blocksize can be variable.

Oracle keeps track of data storage with the help of information stored in the System tablespace. The System tablespace contains the Data Dictionary, indexes and clusters. A data dictionary is a special collection of tables that contains information about all user objects in the database.

Stored procedures and functions can be stored and executed within the database. These can be developed in Oracle's proprietary procedural extension to SQL, PL/SQL, or in the object-oriented language Java.

An Oracle database installation traditionally comes with a default schema called scott. After the sample tables have been created, the user can log into the database with the user scott and password tiger. These names come from Bruce Scott who was one of the first employees at Oracle (then Software Development Laboratories). Tiger was the name of his cat.

History

Software Development Laboratories was founded in 1977. In 1979 SDL changed its company name to Relational Software, Inc (RSI) and introduced their product Oracle V2 as an early commercial relational database system. The version did not support transactions but implemented the basic SQL functionality of queries and joins. There was no version 1, instead the first version was called version 2 as a marketing strategy.

In 1983, RSI was renamed Oracle Corporation to more closely align itself with its flagship product. Oracle version 3 was released which had been re-written in the C Programming Language and supported commit and rollback transaction functionalities. Platform support was extended to UNIX with this version, which until then had run on Digital VAX/VMS systems.

In 1984, Oracle version 4 was released which supported read consistency.

Starting 1985, Oracle began supporting the Client-Server model, with networks becoming available in the mid 80s. Oracle version 5.0 supported distributed querying.

In 1988, Oracle entered the products market and developed its ERP product - Oracle Financials based on the Oracle Relational Database. Oracle version 6 was released with support for PL/SQL, row-level locking and hot backups.

In 1992, Oracle version 7 was released with support for integrity constraints, stored procedures and triggers.

In 1997, Oracle version 8 was released with support for object-oriented development and multimedia applications.

In 1999, Oracle 8i was released which is more in tune with the needs of the Internet (The i in the name stands for "Internet"). The database has a native Java Virtual Machine.

In 2001, Oracle 9i was released with 400 new features including the facilty to read and write XML documents.

In 2003, Oracle 10g was released. The g stands for "Grid"; one of the sales points of 10g is that it's "grid computing ready". 10g also provided an option for Oracle RAC, or Real Application Clusters, a computer cluster database.

Version numbering conventions

Oracle's numbering conventions have confused many people; they warrant a brief explanation. Since version 8, Oracle's RDBMS release numbering has been as follows:

Oracle 8: 8.0.3 - 8.0.6
Oracle 8i: 8.1.5.0 - 8.1.7.4
Oracle 9i (Release 1): 9.0.1.0 - 9.0.1.4
Oracle 9i (Release 2): 9.2.0.1 - 9.2.0.6 (Latest current patchset as of December 2004)
Oracle 10g: 10.1.0.2 - 10.1.0.3 (Latest current patchset as of August 2004)

Oracle releases an 'Enterprise Edition' and a 'Standard Edition' of the database, with the Enterprise Edition containing more features. Recently (from 10g), Oracle has added 'Standard Edition One', which has some additional feature restrictions.
Eg. 8.0.3 (major.minor.patch) means 8 major changes have been made, 0 minor changes have been made and 3 patches have been made.

Host platforms

In the past, prior to version 9i, Oracle has ported the database engine to a wide variety of platforms.

More recently, Oracle has consolidated on a smaller range of operating system platforms.

As of December 2004, the platforms supported for Oracle 10g were:

Linux x86
z/Linux
Linux Itanium
Microsoft Windows (32-bit)
Microsoft Windows (64-bit Itanium)
Solaris x86
Solaris SPARC (64-bit)
AIX5L
HP-UX PA-RISC
HP-UX Itanium
HP Tru64 UNIX
IBM z/OS
Mac OS X Server
Related products and tools

In addition to its powerful RDBMS, Oracle has released several related suites of tools and applications.
Oracle Application Server is a J2EE-based application server for developing and deploying applications using internet technologies and a browser.
Oracle e-Business Suite is a collection of applications for Enterprise resource planning (including Oracle Financials), Customer relationship management and Human Resources (Oracle HR).
Oracle Collaboration Suite contains messaging, groupware and collaboration applications.

Development of applications is commonly performed in Java (using Oracle JDeveloper) or through PL/SQL (using Oracle Forms and Oracle Reports). Oracle is also moving toward 'wizard' driven environment to enable non-programmers to produce simple data-driven applications.

These have historically followed their own release numbering and naming conventions. As of the RDBMS 10g release, Oracle seems to be making an effort to standardize all current versions of its major products on the "10g" label.

Getting started

Users new to Oracle who need to get it up and running should check out the online documentation, the Oracle Technology Network site and the comp.databases.oracle Usenet discussion group. Fully-featured evaluation software can also be downloaded from the Technet site (see below). Users who have Oracle support contracts should turn to Oracle's Metalink website, see below (requires password).